pH is the measure of Soil Acidity Too much is bad - too little is bad And it keeps changing If soil pH is right - leave it alone. If soil pH is wrong - you should add limestone to increase it or sulfur to lower it. Until you correct soil pH, you are wasting time - energy - money because fertilizers can't dissolve in very acid or very alkaline soil and can be almost useless. Fertilizers will dissolve when you water them into soil at the proper pH and this is the only way your trees, plants, flowers, fruits, vegetables, and lawns can be fed. The same is true for the normal bacteria which live in the soil and promote soil enrichment. They function best in neutral or slightly acid soil. The Kelway® Soil pHD can more than pay for itself the first time it is used. The instructions include guidance on how to adjust soil pH. To test soil acidity the tester is inserted 2 inches into moist soil, and in minutes - the pH is displayed on the meter. The Soil pHD creates its own power, really, infinitely tiny current between the tester's two different metal rings. No batteries needed - ever. Kelway Soil PHD SPHRegular price: $65.30Sale price: $57.75 Conditioning Film for Kelway PHD Soil pH MetersConditioning Film for cleaning and conditioning the electrodes of the HB-12 Soil and Moisture pH Meter after each use for more accurate readings. Each sheet is good for 20 uses. Pack of 12 3" x 4" sheets complete with instructions. Availability: Usually ships the same business day KCP$9.95, 3/$26.85, 6/$47.70 Need more information? Please feel free to contact us at 1-800-592-6940 - Ask for Extension 547 or Internet Sales.